This invention relates to a method for measuring coagulation rate or clotting ability of a person's blood. This invention also relates to an associated device for performing an in vivo measurement of coagulation rate.
Some people's blood is prone to clotting. For example, clots may form in the vessels of the legs. This condition is known as phlebitis of the legs. Clot particles occasionally break off and flow along the venous system to the heart and from there to the lungs. In the lungs the clot may form a pulmonary embolus. If the embolus is large enough, death is the result. Less drastic effects are the collapse of a lung or a lung infection.
In other cases, patients are afflicted with an atrial fibrillation. The atria do not contract properly and some blood is not ejected but rather circulates in eddy currents in the atria and forms clots. These clots eventually pass out of the hear and may end up in the brain, resulting in a stoke. The third leading cause of death in the United States is stroke. Even if a victim does not die from a stoke, his or her brain function may become severely impaired by the death of large numbers of brain cells.
One method of treating people who are known to be afflicted with a tendency towards intravascular clot formation is to thin the blood with an anticoagulant composition such as coumadin. This composition this the blood and has no complications, when used at proper concentrations. The problem is that coumadin has a narrow range of effective concentrations. If the concentration is too low, the composition does not effectively thin the blood. If the concentration is too high, excessive bleeding results. This can be dangerous where there is even a small head trauma. The excessive bleeding produces a stroke and can result in death.